High-Power RF Sources for Advanced Accelerator R and D

Improved understanding of the processes that limit RF electric and magnetic fields at material surfaces is needed to enable development of new accelerator structures that can sustain accelerating fields in the range of 150 MeV/m, and in turn to allow design of a future multi-TeV electron-positron collider. For this purpose, stand-alone RF sources are needed to carry out RF breakdown and pulsed heating studies on test structures of novel design, structures fabricated from a variety of alternate materials, and structures processed using alternate techniques. These new RF sources should operate at frequencies above 11.4 GHz (where high-power klystrons built for NLC are already available), and should incorporate a high-power phase-stable amplifier or harmonic multiplier delivering several 10's of MW's of peak power in near-microsecond-long pulses at a repetition rate in the range of 100 Hz. These sources would be operated together with pulse compression systems that can multiply the peak power to 100's of MW. This paper briefly reviews current performance of the Yale/Omega-P 34-GHz magnicon as a point of departure, and discusses alternative candidates for RF sources at other frequencies. These include a 30-GHz, 50 MW magnicon; and 20.0, 22.8, 34.3, and 45.6 GHz harmonic multipliers